Biological and biochemical characterization of tissue specific cell-cell ligands isolated from membranes of embryonic chick and mouse cells. Developmentally regulated changes in the interactions of embryonic cells with lectins. Molecular analysis of genomic changes associated with early determination and differentiation of embryonic neural retina cells, at the level of specific products and morphogenetic processes. Interactions between the cell surface and the genome which direct the differentiation of embryonic cells.